Wireless communications access, on which our society and economy is growing increasingly dependent, is becoming pervasive in all aspects of daily societal functions. For example, wireless communication has become increasingly available to users on board mobile platforms such as land vehicles, aircraft, spacecraft, watercraft or the like. Wireless communication services for passengers of mobile platforms include Internet access, e.g., e-mail and web browsing, live television, voice services, virtual private network access and other interactive and real time services.
Wireless communication platforms for remote, hard to access, or mobile user terminals, e.g., mobile platforms, often use communication satellites that can provide service coverage over large geographic footprints, often including remote land-based or water-based regions. Generally, base stations, e.g., a ground base station, send information (e.g., data) to the user terminals through a bent pipe via one or more satellites. More specifically, the base stations send information on a forward link to the satellite that receives, amplifies and re-transmits the information to an antenna of one or more fixed or mobile user terminals. The user terminals, in turn, can send data back to the base stations via the satellite. The base stations can provide the user terminals with links to the Internet, public switched telephone networks, and/or other public or private networks, servers and services.
Modern satellites and other cellular communication systems often employ a number of spot beams providing a beam laydown that forms coverage over a geographic region that may be divided into a plurality of cells. In a communication system using spot beams, the same frequency may be used at the same time in two or more cells. These beams may be configured to maintain a predetermined co-polar isolation (e.g., carrier-to-interference ratio) value in order to minimize the interference among beams. This is called spatial isolation and spatial reuse. In one typical parlance, each spot beam may be assigned a color to create a color pattern that matches a frequency reuse pattern. Identical frequencies, then, may be reused by different beams with the same color.
A number of satellites are currently being developed that include a large reflector, some on the magnitude of 22 meters in diameter, which may enable formation of narrower spot beams and maximum frequency reuse. Some of these satellites have reflectors that are deployable from a stowed configuration to a deployed configuration in which its surface may form a parabola. The deployment is often performed in a space environment, conducted remotely from a ground mission control center.
The performance requirements of a system often assume that the satellite's deployed reflector has an ideal surface (ideally-shaped). But the larger surfaces of some reflectors and their deployment often create distortion that results in a non-ideal surface (non-ideally-shaped). That is, the reflector surface is often not accurately and repeatedly predictable. And when the surface deviates from its ideal shape, performance may degrade. For example, the carrier-to-interference (C/I) ratio may degrade because side-lobe performance cannot be accurately predicted and taken into account.